Hypertensive and catecholamine response to tracheal intubation in patients with pregnancy-induced hypertension

The pressor and catecholamine responses to laryngoscopy and intubation were studied in nine patients with pregnancy-induced hypertension (PIH) and in eight normotensive controls. Five of the PIH patients had received oral labetalol as antihypertensive therapy. Mean arterial pressure (MAP) increased significantly from the pre-induction value in all groups 1 min after intubation, and also at 3 min in those with PIH who had not received labetalol. Arterial pressure was significantly greater in both PIH groups than in the control group at all times. However, the percentage increase in MAP on intubation was significantly less in the labetalol treated group than in either the untreated or the control groups. There were no significant differences between the groups in plasma concentrations of either noradrenaline or adrenaline; noradrenaline concentration increased significantly after intubation only in the control group. Labetalol appears to confer some protection against the pressor response to intubation in parturients with PIH.